Improvement in screw-threading machines



UNITED STATES .PATENT OFFICE.

JOHN ORUM, OF RAMAPO, ASSIGNOR TO HENRY L. PIERSON, OF

' NEW YORK, N. Y.

IMPROVEMENT IN SCREW-THREADING MACHINES'.

Specification forming part of Letters Patent No. 5,794, dated September19, 1848.

To all whom it may concern:

Be it known that I, JOHN CRUM, of Ramapo, in the county of Rockland andState of New York,have invented new and usefullmprovements in Machinesfor Cutting the Threads of Wood-Screws; and I do hereby declare that thefollowing is a full, clear, and exact description of the principle orcharacter which distinguishes them from all other things before knownand of the manner-of making, con-q structing, and using the same,reference being had to the accompanying drawings, making part of thisspecification, in which- Figure 1 is a plan of the machine; Fig. 2, anelevation of the left-hand side; Fig. 3, a longitudinal vertical sectiontaken at the line :r of Fig. l and looking in the direction of thearrow; Fig. 4, a frontelevation, and Fig. 5 ahorizontal section taken atthe line z z of Fig. 2.

The same letters indicate like parts in all the figures.

In machinery for threading screws as heretofore made the pitch of thethread is given either by moving the dies along that part of the blankwhich is to be threaded (the blank being rotated by jaws on a spindle)'or by movingthe blank itself while it rotates with the jaws that holdit on the end of a spindle. In general the blank is held still bygrippingjaws andthe dies have a rotary motion and a series ofreciprocating motions to chase or cnt the thread, which is completed bya series of operations to insure a goed thread. In one machineextensively used the blanks are fed by hand in holes made in the rim ofa wheel which has an intermittent motion to remove the threaded screwand present the blanks to the dies, which of necessity must have areciprocating motion to traverse on the shank of the blank to form thethread. Experience has shown this to besomewhat defective and to becomplex and therefore liable to ,derangement Y The object of myinvention is mainly t avoid the defects of the last-named machine;andthe nature of my invention consists in giving a reciprocating motionto a carriage in which is hung the shaft of the` carrying and holdingwheel to draw the stem of the blank fronrthe dies as they rotateA togive the pitch to the thread and toreturn it tothe dies for a successionof operations until .the thread is cut, this series of motions beinggiven 'by a simple segment cog-Wheehthe cogs of which act alternately onan upper and a lower rack connected with the carriage, and also ingiving to the carrying and holding wheel an intermittent rotary motion(to remove a threaded screw and present a blank) from a Wheel belowprovided with a pin on its face, which at every rotation lifts a leverthe upper end of which is provided with a hand that 'acts on the teethofa ratchet-wheel on the shaft of the carrying-wheel to turn it therequired distance for the presentation of a blank, the wheel thatcarries the lifting-pin being turned a part of a revolution for each cutof the dies by an arm on the shaft of the cam that'closes the dies,thenumber of teeth or pinson the wheel that are to be struck by the.armen the crank-shaft being such foreach pin on the other face of theWheel as to correspond with the number of cuts to be given by the diesfor the completion of the thread of the screw.

The nature of my invention also consists in holding the blanks whileunder the operation of the dies by the pressure of a spring-rollervwithin the rim.

The last part of my invention consists in closing the dies for thecutting of the threads by means of a cam which makes one revolution foreach cut and acts by means of aslidhollow arbor of the jaws to closethem when this is combined with a sliding wedge-piece interposed betweenthe sliding rod andthe levei` to increase the depth of the cut at cachoperation, the said Wedge-piece being Amade to slide for this purpose bymeans of another cam combined therewith.

AIn the accompanying drawings, a represents a frame properly adapted tothe purposeand b the main driving-shaft, with a pulley @from which abelt d passes to a-pnlley e on'a hollow mandrel f, that carriesthejawsgg g; in which are secured dies or chases 71.v h, made Vin theusual manner. y The jaws are jointed to ears i z' on the end of themandrehwith springs j j interposed', that tend constantly to keep thejaws open, and the rear end ofthe lng rod on a lever that forces a rodinthe k, that slides within the mandrel. `'The rear end of this rod passesout of the mandrel and is acted on when the jaws are to be closed by thepoint of an adjustable screw Z on the upper end of a lever m, the lowerarm of the said lever being acted upon by a sliding rod n, that bearsagainst the face of a cam o on a transverse shaft p. The form of thiscam is such that from the point l to 2, extending one-half of thecircumference, it is concentric at the point 2. It suddenly' runs outfrom the center to close the jaws, and therefore to make the dies graspthe shank of the blank, and then from this sudden swell to the point 3it gradually runs out from the center to increase the bite of the dies,and then by a radial line it runs back to the point of beginning topermit the springs to force open the jaws that the screw-blank may berun back for a repetition of the operation. This cam receives itsmotions from the mandrel by a train of cog-wheels q r s, the one q beingon the shaft of the cam and engaging with the cogs of the one r, whichis on the shaft of the wheel s, that is actuated by an endless screwt onthe mandrel.

Between the lower arm of the lever m and the sliding rod n there isinterposed a wedgeformed slide n', placed at right angles with thesliding rod n. The end 'u of this slide is forced bya spring w againstthe face of a series of cam-formed projections x on the face of a wheely on a shaft e, the periphery of the said wheel being provided withteeth a', which strike against a pawl or hand h', jointed to the mainframe, the shaft of the said wheel yhaving its bearings in a frame a3,attached to and moved by the lever m, so that at every back motion ofthe lower end of this lever to open the jaws the wheel y is turned aportion of a revolution that the cam-formed projections .fr may act onthe end of the wedgeformed slide and force it back, and thus cause thethreading-cam at each operation to close the cutting-dies more, and inthis way complete the cutting of the thread by a series of operations.lThe cam-formed projections w are a series of planes inclined to theplane of the face of the wheel from which they project, and the lengthof each is such relatively to their motion as that each shall move. itswhole length for the complete cutting of one screw, and of course thenumber of these camformed projections will depend on the diameter of thewheel to which they are attached and to the extent of the motion of thesaid wheel. Y

The screw-blanks c are inserted in holeslin the rim d of what4 is calledthe carrying and holding wheel e', the rim being made to project fromthe face of the wheel suliiciently for this purpose. The shaft f of thiswheel runs in standards g of a carriage h', that runs on ways t i", andthis carriage receives a reciprocating motion to move the blank towardand from the chasers or dies by a segment cog-wheel 7" on the shaft ofthe threading-cam. The cogs extend over a little less than one-half ofthe circumference, and alternately act on the teeth of a lower rack 7cto move the carryingwheel toward the cutting-dies and then on 'the cogsof an upper rack Z to run itback to form the thread, the said racksbeing formed in the opening of a bar attached to the carriage of thecarrying-wheel. In this way the motions back and forth of the carriageare given to determine the pitch of the threads and to return the screwfor the repetition of the operation. So soon as a screw has beenthreaded it must be carried away and a blank presented to the dies. Thisis done in the following manner: On the shaft of the carrying-wheelthere is a ratchet-wheel m', which is turned by a hand n on the end of alever o', that turns onra fulcrum at "p The lowerarrn is bent, as at q',so that when lifted the hand on the upper end turns the ratchet-wheel,and with it the carrying-wheel, the required distance to carry off thethreaded blank and present a new one.

The lever is operated in the following manner: O11 the threading-camshaft there is an arm a" which, at every rotation of the shaft strikesone of a series of pins s', projecting from a wheel t', to turn it adistance equal to the space between the centers of any two of thesepins, and on the other face of this Wheel there is a pin u', which atevery entire revolution of the wheel strikes'und'er the bent arm of thelever 0 and gives it the requisite motion to turn the carrying-wheel.Back of the lever o there is a standard a2, with a setscrew b2, againstwhich the lever strikes when thrown back by the weight of the bent vpartq', so that by the set of this screw the extent of motion of the leverand the carrying-wheel can be determined. The position of the arm r onthe segment cog-wheel shaft relatively to the segment of cogs should besuch that the carrying-wheel will be turned for removing the threadedscrew and presentinga p blank when the carriage is farthest from thejaws, and the number of pins sf on the wheel t must be equal to thenumber of times it is intended that the chasers or dies shall pass overthe blank to complete the thread; but, if desired, this number may bedoubled, trebled, Jac., by having two, three, &c., pins u on the otherface of the wheel. It is, however, preferred to have it as described. Inthis way it will be seen that the carryingwheelcarries the blanks towardthe jaws and inserts the blank in the open dies and moves it back toform the thread, and that these motions are repeated a given number oftimes until the thread is completely chased or cut, and that whencompleted the carrying-wheel is turned far enough around to remove thethreaded screw and present a blank to the jaws to undergo the sameseries of operations. While the screw is being cut or chased, it is heldin its hole in the rim of the carryingwheel by means of a roller owithin the rim of the wheel and turning on a stud-pin at the end ofa`lever w', which turns on a fulcrumpin the roller being held againstthe inner periphery of the rim of the wheel by a pressure-screw y thatbears against the lower end of the lever, so that as the blank iscarried up by the wheel to be presented to the dies the pressure of thisroller against the head holds it firmly in the rim of the Wheel.

The machine can be made doublefor threading two screws at one and thesame time, as shown in the drawings, by having two carrying-wheels onthe same shaft and two mandrels, with their jaws, dies, and slidingrods, the two mandrels being geared together by two cog-wheels z a.

It will be obvious from the foregoing that, instead of the segmentcog-wheel for giving the reciprocating motions to the carriage of thecarrying-wheel, this may be done by a segment volute cam, the face ofwhich shall act alternately against the front and back faces of the openspace of the bar attached to the carriage, as the objectis simply togive a regular reciprocating motion to the carriage, particularly duringthe operation of threading, for during that operation the motion of thecarriage must be regular to give a regu# lar pitch to the thread. `As itis only important to give a regular motion to the carriage in theoperation of threading, the segmentcog or the volute cam need only actin this direction, and the motionV to run back the car- Y riage for thepresentation of' the blank may be given bya separate cam of a moresudden curve, or an armof greater length to perform the return motionfaster; but as these are wellknown mechanical equivalent-s they aresimply named to indicate the various modes y1n which this partof myinvention may be applied. j

What I claim as my invention, and desire to secure by Letters Patent,is-` l. The carrying-wheel on the reciprocating carriage operatedsubstantially as described, in combination with the dies in the jaws ofthe mandrel, substantially as described,where by the stem of the screwis moved in and out for the chasing or cutting of the thread of thescrew by a series of operations, as described.

2. The method of holding the blanks in the rim of the carrying-wheel bycombining with the rim of the wheel the pressure-roller, substantiallyas described.

l3. The method of increasing the depth of the cut of the chasers or diesyin the jaws of the rotating mandrel for each cut in the series by thethreading-cam, andthe wedgeformed slide operated substantially asdescribed, in combination with the carrying and holding wheel, asdescribed.

JOHN CRUM. f Witnesses: J. T. DEAN, WEs'rEL W. POWELL.

